Semiconductor curing light system useful for curing light activated composite materials

ABSTRACT

A curing light system useful for curing light activated composite materials is disclosed. The system includes a light emitting semiconductor device, a primary heat sink and a secondary heat sink. Various configurations of light emitting semiconductor chips and heat sinks are disclosed, as well as various structures and methods for driving, controlling and using them.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 09/405,373 filed on Sep. 24, 1999, now U.S. Pat.No. 6,331,111, and priority is claimed thereto. Priority is also claimedto U.S. Provisional Patent Application Ser. No. 60/304,324 filed on Jul.10, 2001.

BACKGROUND OF THE INVENTION

The inventions relate to the field of curing lights that may be used tocure light activated composite materials. More particularly, theinventions relate to curing lights of various configurations that usesemiconductor light sources to provide light of a wavelength and powerlevel desired to effect curing.

In the prior art, various light sources have been used for the purposeof curing composite materials. Halogen bulbs, fluorescent bulbs, xenonbulbs, and plasma-arc lights have been used. More recently, there havebeen some efforts to produce an effective curing light using lightemitting diodes (LED's), but those efforts have not met with widespreadacceptance in the marketplace.

The prior art described above suffers from several disadvantages. First,many of those prior art lights generate a wide spectrum of light ratherthan light just of the desired wavelength for composite curing.Consequently, those prior art lights generate unnecessary heat. Second,many of those prior art lights require light transfer systems such as alight guide or fiber, which many embodiments of the present inventionomit, providing a smaller and more efficient unit. Third, many of theprior art systems require an elaborate cooling system to handle heat,creating a large, heavy and expensive curing light. Many embodiments ofthe invention use a unique heat sink structure that avoids the need forcomplicated, noisy and expensive cooling systems. Additional points ofdifference between the inventions and the prior art will become apparentupon reading the text below in conjunction with the appended drawings.

SUMMARY OF INVENTION

It is an object of some embodiments of the invention to provide a curinglight system that uses a semiconductor light source to produce lightcapable of curing composite materials. Curing composite materials willinvolve polymerizing monomers into durable polymers. Various physical,electrical and semiconductor structures, materials and methods areprovided to achieve this object. Additional objects, features andadvantages of the invention will become apparent to those skilled in theart upon reading the specification and reviewing the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a battery-powered dental curing light that uses a singlelight emitting diode chip as a light source.

FIG. 2 depicts a cross-section of the light of FIG. 1.

FIG. 3 depicts an AC-powered dental curing light that uses a singlelight emitting diode chip as a light source.

FIG. 4 depicts a cross section of the light of FIG. 3.

FIG. 5 depicts a battery-powered curing light that uses two lightemitting diode chips as a light source.

FIG. 6 depicts a cross-section of the light of FIG. 5.

FIG. 7 depicts an AC-powered curing light that uses two light emittingdiode chips as a light source.

FIG. 8 depicts a cross-section of the light of FIG. 7.

FIG. 9 depicts a battery-powered curing light that uses three lightemitting diode chips as a light source.

FIG. 10 depicts a cross-section of the light of FIG. 9.

FIG. 11 depicts an AC-powered curing light that uses three lightemitting diode chips as a light source.

FIG. 12 depicts a cross section of the light of FIG. 11.

FIG. 13 depicts a battery-powered curing light that uses fivesemiconductor chip modules mounted on a heat sink in a manner that thelight they emit is collected by a reflector apparatus and focused by alens means onto a light transport mechanism, such as a light guide,plastic stack or fiber.

FIG. 14 depicts a cross-section of the light of FIG. 13.

FIG. 15 depicts an alternative embodiment of the light of FIG. 13, inthe light transport mechanism is replace by a distally-located mirrorwhich reflects generally coherent light emitted from the light source ina desired direction for use.

FIG. 16 a depicts a light which uses a plurality of light emittingsemiconductor modules mounted on a heat sink as a light source, afocusing means to produce a generally coherent beam of light, and alight transport means such as optically conductive cable fortransporting light to a location remote from the light source for use.

FIG. 16 b depicts a cross section of the light of FIG. 16 a.

FIG. 17 a depicts a gross cross section of a light emitting diode chipthat uses an insulative substrate.

FIG. 17 b depicts a gross cross section of a light emitting diode chipthat uses a conductive substrate.

FIG. 18 a depicts epitaxial layers of a light emitting diode chip thatuses an insulative substrate.

FIG. 18 b depicts epitaxial layers of a light emitting diode chip thatuses a conductive substrate.

FIG. 19 a depicts a top view of a light emitting diode chip array(single chip) with a conductive substrate.

FIG. 19 b depicts a top view of a top view of a light emitting diodechip array (single chip) with an insulative substrate.

FIG. 20 a depicts a side view of a chip package for a light emittingchip that shows a light emitting diode chip with an insulative substratemounted in a well of a heat sink, with electrical connections and lightemission shown.

FIG. 20 b depicts a perspective view of a chip package for a lightemitting chip with an insulative substrate that shows a chip arraymounted in a well of a heat sink.

FIG. 21 a depicts a side view of a chip package for a light emittingchip that shows a light emitting diode chip with a conductive substratemounted in a well of a heat sink, with electrical connections and lightemission shown.

FIG. 21 b depicts a perspective view of a chip package for a lightemitting chip with a conductive substrate that shows a chip arraymounted in a well of a heat sink.

FIG. 22 a depicts a side view of a chip package for a light emittingchip mounted in a well of a heat sink according to the so-called ‘flipchip’ design, the chip having an insulative substrate.

FIG. 22 b depicts a side view of a flip chip mounted on a flip chip pad.

FIG. 22 c depicts a perspective view of a flip chip pad.

FIG. 22 d depicts a perspective view of the chip package of FIG. 22 a.

FIG. 23 depicts a side view of a flip chip package with a conductivesusbtrate.

FIG. 24 a depicts a side view of a light emitting diode chip packageincluding the chip (insulative substrate) and heat sink surface mountarrangement with a protective dome, lens or cover.

FIG. 24 b depicts a side view of a light emitting diode chip packageincluding the chip (conductive substrate) and heat sink surface mountarrangement with a protective dome, lens or cover.

FIG. 25 a depicts an array of light emitting chips with insulativesubstrates in surface mount arrangement in a single well of a heat sink.

FIG. 25 b depicts a perspective view of the array of surface-mountedchips of FIG. 25 a.

FIG. 26 a depicts an array of light emitting chips with conductivesubstrates in surface mount arrangement in a single well of a heat sink.

FIG. 26 b depicts a perspective view of the array of surface-mountedchips of FIG. 26 a.

FIG. 27 a depicts an array of light emitting chips with insulativesubstrates in surface mount arrangement in individual sub-wells of awell of a heat sink.

FIG. 27 b depicts a perspective view of the array of surface-mountedchips of FIG. 27 a.

FIG. 28 a depicts an array of light emitting chips with conductivesubstrates in surface mount arrangement in individual sub-wells of awell of a heat sink.

FIG. 28 b depicts a perspective view of the array of surface-mountedchips of FIG. 28 a.

FIG. 29 a depicts a light emitting surface mount chip package includingarray of chips, heat sink and protective dome, lens or cover accordingto the chip and surface mount configuration of FIG. 25 a above.

FIG. 29 b depicts a light emitting surface mount chip package includingarray of chips, heat sink and protective dome, lens or cover accordingto the chip and surface mount configuration of FIG. 26 a above.

FIG. 30 a depicts a light emitting surface mount chip package includingarray of chips in sub-wells, heat sink and protective dome, lens orcover according to the chip and surface mount configuration of FIG. 27 aabove.

FIG. 30 b depicts a light emitting surface mount chip package includingarray of chips in sub-wells, heat sink and protective dome, lens orcover according to the chip and surface mount configuration of FIG. 28 aabove.

FIG. 31 a depicts a side view of a single surface mount light emittingdiode chip mounted to an elongate heat sink in a manner such that lightfrom the chip is emitted at generally a 90 degree angle to thelongitudinal axis of the elongate heat sink.

FIG. 31 b depicts a bottom view of the device of FIG. 31 a.

FIG. 32 a depicts a cross-sectional side view of an elongate heat sinkhaving two light emitting semiconductor chips mounted on it in an angledorientation in order to present overlapping light beams for an enhanceddensity light footprint.

FIG. 32 b depicts a top view of the device of FIG. 32 a.

FIG. 33 a depicts a cross-sectional side view of an elongate heat sinkhaving three light emitting semiconductor chips mounted on it in anangled orientation in order to present overlapping light beams for anenhanced density light footprint.

FIG. 33 b depicts a top view of the device of FIG. 33 a.

FIG. 33 c depicts a top view of the heat sink of FIG. 33 a and 33 b topermit the reader to understand the angular orientation of the lightemitting semiconductor chips.

FIG. 34 a depicts a light shield which may be used in conjunction withcuring lights of the invention to shield human eyes from light emittingby the curing light.

FIG. 34 b depicts a focus lens which may be used to focus light emittedby curing lights of the invention in order to present a denser lightfootprint.

FIG. 35 depicts a block diagram of control circuitry that may be usedwith the embodiments of the inventions that utilize AC power.

FIG. 36 depicts by a block diagram of control circuitry that may be usedwith the embodiments of the inventions that utilize battery power.

FIG. 37 depicts a graph of electrical current input I to the lightemitting semiconductor chip(s) of the curing light versus time in apulsed power input scheme in order to enhance light power output fromthe chip(s) and in order to avoid light intensity dimunition due to theheat effect.

FIG. 38 depicts a graph of total light intensity output versus time inorder to permit the reader to compare light intensity output when acurrent input pulsing scheme such as that of FIG. 37 is used to atraditional continuous wave current input approach which generates aheat effect is used.

DETAILED DESCRIPTION

The inventions include various embodiments of curing light systemsuseful for curing light activated composite materials, principally bypolymerizing monomers into durable polymers. The invented curing lightsystems have application in a variety of fields, including but notlimited to medicine and dentistry where composite materials with aphotoinitiator are used. The photoinitiator absorbs light of aparticular wavelength and causes polymerization of the monomers intopolymers.

Composite materials are applied to a surface and later cured by avariety of methods. One method includes use of a photoinitiator ormultiple photoinitiators in the composite material. After the compositematerial has been placed in a desired location, light of a wavelengththat activates the photoinitiator is applied to the composite. The lightactivates the photoinitiator and initiates curing of the compositematerial. In order to effect complete curing, the light must be of awavelength to which the photoinitiator is sensitive, the light must beof a power level that will cause curing, and the light must be appliedto the composite material for a sufficient duration of time. Althoughthe light used to activate the photoinitiator must be of a wavelength towhich a photoinitiator is sensitive, the light can come from a varietyof sources, including gas lasers solid state lasers, laser diodes, lightemitting diodes, plasma-arc lights, xenon-arc lights, and conventionallamps. In the present inventions, light is produced from a variety ofdifferent semiconductor chips arranged in numerous configurations.

FIG. 1 depicts a battery-powered curing light 100 that uses a singlelight emitting diode chip as a light source. FIG. 2 depicts across-section of the light 100 of FIG. 1. The portable curing lightsystem 100 includes a light source module 102 which generates light of adesired wavelength or multiple wavelengths for activating aphotoinitiator or multiple photoinitiators and initiating curing of alight activated composite material. The light source module 102 has alight shield 103 for blocking light generated by the light emittingsemiconductor chip(s) 150 from reaching human eyes and skin. The lightemitting semiconductor chip(s) 150 are located at the distal end of thecuring light, and at the distal end of the light source module 102. Thechip(s) 150 are oriented to emit light at generally a right angle withthe longitudinal axis of the light source module or the longitudinalaxis of the curing light handpiece, although chips could be mounted toemit light at from about a 45 degree angle to about a 135 degree anglewith the longitudinal axis of the light source module, heat sink, orhandpiece as desired. The curing light system 100 includes a housing 104for containing and protecting electronic circuits and a DC battery pack.

A switch 105 a is provided on the top of the housing 104 facing adirection opposite from the direction that light would be emitted fromthe light source module 103. A second switch 105 b is provided on theside of the housing. The switches 105 a and 105 b are devices such as abutton or trigger for turning the light emission of the curing light onand off. A timer 106 is provided to control the duration of time thatthe curing light emits a beam of light. Control buttons to set andadjust the timer are depicted as 151 a and 151 b.

An audible indicator or beeper may be provided in some embodiments ofthe invention to indicate when light emission from the curing lightbegins and ends. A first light emitting diode indicator lamp 107 islocated on the housing in a visible location in order to indicate to theuser low battery power. A second light emitting diode indicator lamp 108is located on the housing in a visible location in order to indicate tothe user that the battery is being charged. A main on/off switch to thecuring light 160 is provided at the rear or proximal end of the housing.A wavelength selector may be provided in some embodiments of theinvention so that the user may select the wavelength of light that hewishes to emit from the curing light, depending on the wavelengthsensitivity of the photoinitiator in the composite material that he isusing. The user may also select a combination of two or more wavelengthsof light to be emitted together in some embodiments of the invention.

A separate battery charger module 109 is included in order to receive ACpower from a traditional wall socket and provide DC power to the curinglight system for both charging the batteries and powering the lightsource and control circuitry when the batteries if desired. The batterycharger module 109 has a cable 109 a and a plug 109 b for plugging intoa receptacle or connector 170 on the proximal end of the curing lighthousing 104. The battery charger module 109 includes circuitry 109 c forcontrolling battery charging of batteries 166.

The light module 102 has a casing 161 that encases an elongate heat sink162. The casing 161 is separated from the heat sink 162 by a bufferlayer 163 such as insulation tape and an air space may be providedtherebetween for heat dissipation. Electrically conductive wires 164 topower the light-emitting semiconductor chip(s) 150. Internally, we cansee that the heat sink 162 is an elongate and curved structure whichpositions a semiconductor chip at its end in a convenient place for usewithout a light guide. At the distal end of the heat sink 162, there maybe a smaller primary heat sink or semiconductor chip module whichincludes a smaller primary heat sink. A semiconductor module may becovered by a protective cover or dome or a focus lens. The heat sink 162may be an elongate structure or other shape as desired. Use of anelongate heat sink 162 rapidly transfer heat away from the chip(s) 150for heat dissipation. If heat transfer and dissipation are not handledadequately, damage to the chip(s) 150 may result, or light output of thechip(2) 150 may be diminished.

The light source module 102 is removable from the housing 104 andinterfaces therewith and mounts thereto by a connection plug 165. One ormore batteries 166 are provided to power the curing light during use.The curing light may have control circuitry 167 located in the housing102. Control circuitry 109 c is located in the power supply 109 forcontrolling battery recharging and direct powering of the curing lightfrom wall outlet power when the batteries are low. The power supply 109has an AC plug 109 d.

A unique advantage of the curing light system depicted in severalembodiments of the invention is that all components, including the lightsource, batteries, control circuitry and user interface are convenientlylocated in or on a handpiece. This results in a very portable, yetcompact and easy to use curing light system. Only when the batteries arebeing charged would the user need to have a cord attached to the curinglight system or even be in the vicinity of AC power. However, the lightsystem can be operated using power from a battery charger when thebattery pack is being charged or when no batteries are being used.

FIG. 3 depicts an AC-powered curing light that uses a single lightemitting diode chip as a light source. FIG. 4 depicts a cross section ofthe light of FIG. 3. Referring to these figures, one embodiment of acuring light system 301 of the invention is depicted. The curing lightsystem 301 includes a handpiece or wand 302, cabling 303, and a powersupply 304 with an AC plug 304 a. Curing light control circuitry 304 bmay be located within the power supply 304 and is remote from the wand302 in order to keep the wand compact and light weight. The handpiece orwand 302 has minimum size, weight and componentry for convenience ofuse. The handpiece 302 includes a housing 305, an on/off switch or lightoutput control 306, an integral light source module 307, and a lightshield 309. The handpiece 302 receives electrical power from cabling303. A cable strain relief device 308 may be provided. A timer 310 maybe provided with timer adjustment buttons 311 and 312 in order tocontrol timed duration of light output from the curing light. Allcontrol circuitry 304 b is located in a module remote from the handpiece302.

Referring to the cross section of FIG. 4, it can be seen that the heatsink 401 may be configured as an elongate device with a planar mountingplatform on its distal end for mounting chips or chip modules thereto.The heat sink has a longitudinal axis, and the light emittingsemiconductor chip(s) may be oriented at an angle with the longitudinalaxis of the heat sink from about 45 to about 135 degrees. In someembodiments of the invention, the chips will be oriented to emit lightat an angle with the heat sink longitudinal axis of 70 to 110 degrees,80 to 100 degrees, or about 90 degrees. The heat sink distal end may becurved as desired to position a light emitting semiconductor device 401thereon to be positioned in a location for convenient use. Thesemiconductor device 402 may be covered with a protective window, domeor focus lens 403. The heat sink may occupy less than 50% of the lengthof the wand, more than 50% of the length of the wand, 60% of the lengthof the wand, 70% of the length of the wand, 80% of the length of thewand, 90% of the length of the wand, or up to 100% of the length of thewand. Electrical wire 404 provides power to the light emittingsemiconductor device 402. Insulation means 405 such as rubber insulatorsor insulation tape separate the heat sink 401 from the casing 305 andprovide for airspace 406 therebetween for ventilation and heatdissipation.

FIG. 5 depicts a battery-powered curing light 501 that uses two lightemitting diode chips as a light source. FIG. 6 depicts a cross-sectionof the light 501 of FIG. 5. The curing light 501 includes a housing orcasing 502 for containing and protecting the curing light components. Aseries of vents 503 are provided in the housing 502 to permit heat toescape therefrom and to permit air circulation therein. At the distalend of the housing 502, a light module 504 is provided. The light module504 may include an angled tip and may be removable and replaceable withother light modules of differing characteristics as desired. A lightshield 505 is provided at the distal end of the light module 504. At theproximal end of the curing light 501, a handle 506 is provided forgrasping the curing light. An on-off switch or trigger 507 is providedon the distal side of the curing light handle 506 for effecting lightemission. On the proximal side of the curing light handle 506, a mainswitch 507 for powering up the curing light 501 is located. A timer 509with timer adjustment buttons 510 and 511 is provided to time theduration of light output. Indicator lights 512 and 513 are provided toindicate low battery and battery charging. A battery charger module 520is provided with a power supply 521, cable 522 and plug 523. The plugfits into receptacle 601 for charging the battery 602 of the curinglight 501. Light module 504 includes a casing 603 that contains anelongate heat sink 604 that is separated from the casing 603 byinsulators 605 to form a ventilating and heat-dissipating air space 606therebetween. Heat sink 604 may include a thermoelectric cooler material608 thereon for enhanced heat dissipation. Electrical wires 607 power apair of light emitting semiconductor devices or modules 609 a and 609 b.The semiconductor devices 609 a and 609 b are mounted on the heat sink604 at a mounting receptacle 611 that has two adjacent angled planesoriented to cause the light output beams from the semiconductor devices609 a and 609 b to overlap to provide an overlapped and enhancedintensity light footprint 610. The mounting planes are oriented at anangle of from about 10 to about 180 degrees with respect to each other.The curing light 501 also includes a timer 620 with timer controlbuttons 621 and 622, and electronic control circuitry 623.

FIG. 7 depicts an AC-powered curing light 701 that uses two lightemitting diode chips as a light source. FIG. 8 depicts a cross-sectionof the light 701 of FIG. 7. The curing light system 701 includes ahandpiece or wand 702, cabling 703, and a power supply 704 with an ACplug 704 a. Control circuitry 704 b is located within the power supply704 and is remote from the wand 702 in order to keep the wand compactand light weight. The handpiece or wand 702 has minimum size, weight andcomponentry for convenience of use. The handpiece 702 includes a housing705, an on/off switch or light output control 706, an integral lightsource module 707, and a light shield 709. The handpiece 702 receiveselectrical power from cabling 703. A cable strain relief device 708 maybe provided. A timer 710 may be provided with timer adjustment buttons711 and 712 in order to control timed duration of light output from thecuring light. All control circuitry 704 b is located in a module remotefrom the handpiece 702. Referring to the cross section of FIG. 8, it canbe seen that the heat sink 801 may be configured as an elongate devicewith a longitudinal axis shared with the longitudinal axis of the wand.The light emitting semiconductor chip 802 and 803 are mounted to theheat sink 801 at an acute angle to each other in order to produce anoverlapping and enhanced intensity light footprint. The heat sink distalend may be curved as desired to position the light emittingsemiconductor devices thereon for convenient use. The semiconductordevices 803 and 803 may be covered by a protective window, dome or focuslens. The heat sink may occupy less than 50% of the length of the wand,more than 50% of the length of the wand, 60% of the length of the wand,70% of the length of the wand, 80% of the length of the wand, 90% of thelength of the wand, or up to 100% of the length of the wand. Electricalwire 804 provides power to the light emitting semiconductor devices 802and 803. Insulation means 805 such as rubber insulators or insulationtape separate the heat sink 801 from the casing 705 and provide forairspace 806 therebetween for ventilation and heat dissipation. Aconnection plug 810 is provided for connecting the power module to thecuring light. Thermoelectric cooler material 820 is optionally providedon the heat sink for enhanced cooling.

FIG. 9 depicts a battery-powered curing light 901 that uses three lightemitting diode chips or modules as a light source. FIG. 10 depicts across-section of the light 901 of FIG. 9. The componentry of this curinglight is as generally described previously except for its three lightemitting diode light source structure. It uses three light emittingdiode chips or chip modules 902 a, 902 b and 902 c arranged incomplementary angled configuration so that the light beams emitted byeach overlap at a desired distance from the light source to form anoverlapped and enhanced intensity light footprint 903.

FIG. 11 depicts an AC-powered curing light 1101 that uses three lightemitting diode chips or modules as a light source. FIG. 12 depicts across-section of the light 1101 of FIG. 11. The componentry of thiscuring light is as generally described previously except for its threelight emitting diode light source structure. It uses three lightemitting diode chips or chip modules 1102 a, 1102 b and 1102 c arrangedin complementary angled configuration so that the light beams emitted byeach overlap at a desired distance from the light source to form anoverlapped and enhanced intensity light footprint 1103.

FIG. 13 depicts a battery-powered curing 1301 light that uses aplurality of semiconductor chip modules mounted on a heat sink in amanner that the light they emit is collected by a reflector apparatusand focused by a lens means onto a light transport mechanism, such as alight guide, plastic stack or fiber 1302. FIG. 14 depicts across-section of the light 1301 of FIG. 13. Many of the components ofthis light are as discussed previously for other curing lightembodiments, and that discussion is not repeated here. However, thelight source and light transport means are very different fromembodiments discussed above. The curing light 1301 includes a housing1303 which has a light transport means 1302 such as a light guide,plastic stack or fiber attached to it. The light transport means 1302transports light from a light module to a remote location for use. Thelight transport means 1302 depicted has a curved distal portion 1304 tocause light 1305 to be emitted in a desired direction, such as at aright angle to the longitudinal axis of the curing light or the lighttransport means. The light transport means may be removable andreplaceable with light guides of different lengths and configurations. Agross or secondary heat sink 1405 is provided for heat removal from thesystem. The secondary heat sink 1405 has a proximal side on which athermoelectric material layer 1406 may be placed to enhance heat removalability. Optionally, a fan 1407 may be provided to improve heat removalefficiency, and vents may be provided in the housing to encourage aircirculation. The secondary heat sink 1405 may have mounted directly orindirectly to it a plurality of semiconductor light emitting chips orchip modules 1409. Those chips 1409 may be mounted to a primary heatsink such as 1410. Light emitted by the chips 1409 will be reflected bya reflector device 1411 such as a mirrored parabolic reflector to anoptional lens or focusing device 1412 which focuses a generally coherentlight beam onto the light transport means 1302. The reflector may be ofa desired shape for directing light, such as frusto-conical, parabolicor otherwise. If the light emitting devices are oriented so that thelight which they emit is substantially directed toward the distal end ofthe curing light, the reflector may be omitted. A battery pack 1415 andcontrol circuitry 1413 are provided.

FIG. 15 depicts an alternative embodiment of the light of FIG. 13. Thecuring light 1501 has no light transport mechanism and instead has alight exit tube 1502 that has a distal end with a mirror or reflector1504 which can reflect a generally coherent light beam 1503 to a lightexit 1505 in a desired direction for use, such as at a generally rightangle to the longitudinal axis of the light module or the curing light.

FIG. 16 a depicts a curing light curing light 1601 that has a lightsource and control module 1602 remotely located from a handpiece 1603connected by a connection means 1604 that includes an opticallyconductive cable and electrical wires for electrical connection. FIG. 16b depicts a cross section of the light of FIG. 16 a. The light sourceand control module 1602 includes a housing 1610 with optional air ventsthereon, electronic control circuitry 1611, an electrical cord withpower plug 1612, a cooling fan 1613 for air circulation and heatdissipation, a heat sink 1615 which may be appropriately shaped toaccept light emitting semiconductor devices on its distal side, such ashaving a concave hemispherical or parabolic portion, and having athermoelectric cooler 1616 on its proximal side for enhanced heatdissipation. A plurality of light emitting semiconductor devices such asLED chip modules 1618 are mounted to the heat sink distal side so thatthey emit light into an optical system such as a focus lens 1619 whichplaces a generally coherent light beam onto the optically conductivecable where it is transported to a distant handpiece 1603 that includesa housing 1651, light exit 1650 for permitting light to be delivered toa composite material to be cured, and various controls such as lighton/off control 1660, timer display 1663, and timer adjustment buttons1661 and 1662. The distal end of the handpiece housing 1670 may beangled from the longitudinal axis of the handpiece in for convenience oflight application to a composite material.

As desired in various embodiments of the inventions, the light sourcemay be a single LED chip, single LED chip array, an array of LED chips,a single diode laser chip, an array of diode laser chips, a VCSEL chipor array, or one or more LED or diode laser modules. The wavelength oflight emitted from the semiconductor light source can be any desiredwavelength or combination of different wavelength, depending on thesensitivity of the photoinitiator(s) in the composite material to becured. Any of the semiconductor and heat sink arrangements describedherein may be used to construct desired curing lights.

Referring to FIG. 17 a, a light emitting diode (“LED”) chip 1701 isdepicted in which the LED structure 1702 has been grown on top of or onone side of an insulative substrate 1703. Electrodes 1704 a and 1704 bare provided to power the LED. In such a structure, all electrodes willbe located on the top surface of the LED. Light is emitted from allsides of the LED as depicted.

A similar LED chip 1710 with a conductive substrate 1711 andaccompanying LED structure 1712 and electrodes 1713 and 1714 is depictedin FIG. 17 b.

FIG. 18 a depicts an example of epitaxial layer configuration 1801 foran LED with an insulative substrate used in the invention. The LEDincludes an electrically insulative substrate such as sapphire 1802. Thesubstrate serves as a carrier, pad or platform on which to grow thechip's epitaxial layers. The first layer placed on the substrate 1802 isa buffer layer 1803, in this case a GaN buffer layer. Use of a bufferlayer reduces defects in the chip which would otherwise arise due todifferences in material properties between the epitaxial layers and thesubstrate. Then a contact layer 1804, such as n-GaN, is provided. Acladding layer 1805 such as n-AIGaN Sub is then provided. Then an activelayer 1806 is provided, such as InGaN multiple quantum wells. The activelayer is where electrons jump from a conduction band to valance and emitenergy which converts to light. On the active layer 1806, anothercladding layer 1807, such as p-AlGaN is provided that also serves toconfine electrons. A contact layer 1808 such as p+ GaN is provided thatis doped for Ohmic contact. The contact layer 1808 has a positiveelectrode 1809 mounted on it. The contact layer 1804 has a negativeelectrode 1810.

FIG. 18 b depicts epitaxial layer configuration 1850 for an LED with aconductive substrate. The LED includes an electrically conductivesubstrate such as SiC 1852 that has an electrode 1851 on it. Thesubstrate serves as a carrier, pad or platform on which to grow thechip's epitaxial layers, and as a negative electrode in the chip. Thefirst layer placed on the substrate 1852 is a buffer layer 1853, such asn-GaN. A cladding layer 1854 such as n-AlGaN is provided followed by anactive layer 1855 such as InGaN with multiple quantum wells. That isfollowed by a cladding layer 1856 such as p-AlGaN and finally a contactlayer 1857 such as p+ GaN that has an electrode 1858 mounted on it.

FIG. 19 a depicts a top view of an LED array on a single chip 1901 witha size a×b on an insulating substrate. The size of a and b are eachgreater than 300 micrometers. Semiconductor materials 1904 are locatedon an electrically insulative substrate (not shown). Positive andnegative electrode pads are provided, each in electrical connection withits respective metal electrode strip 1902 and 1903 arranged in a row andcolumn formation (8 columns shown) to create the array and power thechip. This structure enables the LED to emit light of greater power thanthat which is possible in a non-array chip.

FIG. 19 b depicts a top view of an LED array on a single chip 1950 witha size a×b on a conductive substrate. Each of sizes a and b is greaterthan 300 micrometers. Semiconductor materials 1952 are located on anelectrically conductive substrate (not shown). Positive electrode padsare provided in electrical connection with a metal strip 1951 arrangedin an array formation to power the chip. The substrate serves as thenegative electrode in the embodiment depicted.

Referring to FIG. 20 a, a side view of a surface mount LED chip package2000 including the LED chip 2001 on a heat sink 2002 is provided. TheLED chip depicted has an insulating substrate and is mounted in a well2004 of the heat sink 2002 by the use of heat conductive and lightreflective adhesive 2003. Light is emitted by the chip in alldirections, and light which is emitted toward the adhesive 2003 or thewell walls is reflected outward in a useful direction 2020. The chip iselectrically connected via wires 2010 a, 2010 b, 2010 c and 2010 d usingintermediary islands 2011 and 2012. The LED chip is located in acircular well 2004 of the heat sink 2002. The circular well is formedwith sides or walls at about a 45 degree angle or other desired angle(such as from about 170 to about 10 degrees) so that light emitted fromthe side of the chip will be reflected from the walls of the well in adesired direction as indicated by arrows in the figure. This allows thehighest possible light intensity to be obtained using a chip of givensize. The well walls may have a light reflective coating to increaseefficiency.

Referring to FIG. 20 b, a perspective view of a LED chip array (singlechip) chip package 2050 including the chip array 2051 on an insulativesubstrate in a well 2052 of a heat sink 2053 is depicted.

Referring to FIG. 21 a, a side view of an LED chip module 2100 isprovided. An LED chip 2101 with a conductive substrate is mounted in acircular well 2103 of a heat sink 2104 by use of heat conductive lightreflective adhesive 2102. A negative electrode 2110 is provided on theheat sink. Positive electrical connection is provided by wire 2105 andisland 2107.

Referring to FIG. 21 b, a chip array package 2150 that includes an LEDchip array 2151 with a conductive substrate mounted in a well 2152 of aheat sink 2153 with an electrode 2154 and wire connection 2155 isdepicted.

FIG. 22 a depicts a side view of a chip package 2200 for a lightemitting diode chip array 2201 mounted in a well 2202 of a heat sink2203 according to the so-called ‘flip chip’ design, the chip having aninsulative substrate. FIG. 22 b depicts a side view of a flip chip 2201mounted on a flip chip pad 2204. FIG. 22 c depicts a perspective view ofa flip chip pad 2204. FIG. 22 d depicts a perspective view of the chippackage 2200 of FIG. 22 a. Intermediate islands or electrode pads 2201 aand 2210 b are provided on the flip chip pad to ease of electricalconnection with the chip. Electrode bumps 2111 a and 2111 b are providedbetween the chip and the pad for electrical connection. The chip has anelectrode 2201 b on top and its epitaxial layers 2201 a facing downtoward the pad 2204 and the bottom of the well 2202. The pad 2204 uppersurface is light reflective so that light is reflected from the pad in auseful direction. The pad 2204 may be coated with a light reflectivefilm, such as Au, Al or Ag. In such a package, all of the light emittedfrom the chip can be reflected back in the light exit direction forhighest light output.

FIG. 23 depicts a flip chip package 2301 in which a chip 2302 with aconductive substrate is mounted upside down (electrode up) on a flipchip pad 2303 with light reflective and heat conductive adhesive 2304 inthe well of a heat sink. Electrical connection takes advantage of theexposed electrode of the chip 2302.

Referring to FIG. 24 a, a high power LED package 2401 is depicted usinga chip 2402 with an insulative substrate mounted in the well of a heatsink 2403 using heat conductive and light reflective adhesive 2404. Theheat sink is surrounded by a known insulating material 2405 that servesthe purpose of protecting electrode and dome connections. The walls andbottom of the well may be covered with a light-reflective coating suchas Al, Au and others to improve light source efficiency. Electrodesand/or connection blocks are provided for electrical connection of thechip. An optical dome or cover 2410 may optionally be provided for thepurpose of protecting the chip and its assemblies, and for the purposeof focusing light emitted by the chip. The dome may be made of any ofthe following materials: plastic, polycarbonate, epoxy, glass and othersuitable materials. The configuration of the well and the dome providefor light emission along an arc of a circle defined by φ. FIG. 24 bdepicts a similar arrangement for a chip package 2450 in which the chip2454 has a conductive substrate and thus when mounted to the heat sink2452 can use an electrode 2455 on the heat sink itself for electricalconnection. Protective dome 2451 and insulating covering 2453 areprovided.

Referring to FIGS. 25 a and 25 b, a chip package 2501 is provided withan array of light emitting semiconductor chips 2504 a, 2504 b, etc.having electrically insulative substrates located in a single well 2502of a heat sink 2503. The chips are mounted by an electrically conductiveand heat conductive adhesive 2605. The chips are electrically connectedto each other by wires 2505 a, 2505 b, etc.

Referring to FIGS. 26 a and 26 b, a chip package 2601 is provided thathas a heat sink 2602 with a single well 2603 and an array of LED chips2604 a, 2604 b, etc. in the well 2603. The chips have electricallyconductive substrates and an electrode 2606 is provided on the heatsink.

Referring to FIG. 27 a, a chip package 2701 is depicted with an array ofLED chips 2702 a, 2702 b, 2702 c, etc. is depicted, with each chiplocated in its own individual sub-well 2703 a, 2703 b, 2703 c in a grosswell 2704 of a heat sink 2705. The chips have electrically insulativesubstrates.

Referring to FIG. 27 b, a chip package 2750 is depicted that has anarray of LED chips 2763 a, 2763 b, 2763 c with electrically conductivesubstrates. Each LED chip is mounted in its own individual sub-well, alllocated within a gross well 2761 of a heat sink 2762.

FIGS. 28 a and 28 b depict a chip package 2801 that has a heat sink 2802with a gross well 2803 and a plurality of sub-wells 2804 therein, eachsub-well having a light emitting chip 2805 with a conductive substratewithin it. The heat sink 2803 has a negative electrode 2806 forelectrical connection.

Referring to FIG. 29 a, an LED chip module 2901 is depicted that has anarray of LED chips 2902 a, 2902 b, etc located in a well 2903 of a heatsink 2904. Insulative covering 2910 as well as a cover or dome 2911 areprovided respectively. The chips of FIG. 29 a have insulativesubstrates.

Referring to FIG. 29 b, an LED chip module 2950 is depicted that has anarray of LED chips 2951 a, 2951 b, etc. located in a well 2955 of a heatsink 2954. Insulative covering 2960 as well as a cover or dome 2961 areprovided respectively. The chips of FIG. 29 b have conductive substratesand an electrode 2959 is provided on the heat sink.

Referring to FIG. 30 a, an LED chip module 3001 is depicted that has anarray of LED chips 3002, with each chip in a sub-well 3003 of a grosswell 3006 of a heat sink 3005 and the entire module covered by aprotective or focus dome 3012. The chips have electrically insulativesubstrates.

Referring to FIG. 30 b, an LED chip module 3050 is depicted that has anarray of LED chips 3051, with each chip in a sub-well 3052 of a grosswell 3055 of a heat sink 3054 and the entire module covered by aprotective or focus dome 3061. The chips have electrically conductivesubstrates and there is an electrode 3056 on the heat sink.

Referring to FIGS. 31 a and 31 b, side and top views of a surface mountchip configuration are depicted for mounting a single LED 3100 or LEDmodule to an elongate heat sink 3101. Electrically conductive wires 3102a and 3102 b and electrodes 3103 a and 3103 b are provided for poweringthe LED. The LED is mounted on a platform 3104 formed on the heat sinkdistal end. Mounting is achieved by use of light reflective and heatconductive adhesive 3105. A cover or focus dome 3106 is provided overthe LED. The heat sink has a longitudinal axis, and the LED is mountedso that the average beam of light that it emits is generally at a 45 to135 degree angle with that axis, and in some instances at a right angleto it.

FIGS. 32 a and 32 b depict side and bottom views of an elongate heatsink 3201 having two light emitting semiconductor chips or modules 3202and 3203 mounted on mounting platforms 3204 a and 3204 b using adhesive3205 a and 3505 b. The chips are mounted on the heat sink in an angledorientation with respect to each other in order to present overlappinglight beams for an enhanced density light footprint 3204. The angle oforientation of the chips is depicted as θ which can be from 20 to 180degrees, or from 30 to 150 degrees, or from 45 to 135 degrees, or from70 to 110 degrees, or from 80 to 100 degrees or about 90 degrees, asdesired. The chips are offset from each other by a desired distance ‘a’,which can range from zero to any desired distance. Wires and electrodesare provided to power the LED's. An optional thermoelectric cooler 3208may be provided.

FIG. 33 a depicts a cross-sectional side view of a light module thatuses three light emitting chips or chip modules. FIG. 33 b depicts abottom view of the same. FIG. 33 c depicts a bottom view of the heatsink. FIG. 33 d depicts a side view of the heat sink. An elongate heatsink 3301 is provided having three light emitting semiconductor chips ormodules 3302, 3303, and 3304 mounted on mounting platforms in an angledorientation with respect to each other in order to present overlappinglight beams for an enhanced density light footprint 3306. The mountingplatforms depicted are generally planar and are arranged to present thedensest useful light footprint. The modules may each include their ownprimary heat sink. The modules or chips may be mounted to the elongateheat sink using a heat conductive or light reflective adhesive asdesired. Electrical wires and electrodes are used to power the chips ormodules. An optional thermoelectric cooler 3308 may be provided. Themounting platforms 3305 a, 3305 b and 3305 c can be seen more clearly inFIGS. 33 c and 33 d. The mounting platforms depicted are arranged incircular fashion at an angular offset θ with respect to each other,which in this case is 120 degrees. More mounting platforms could beused, and any desired arrangement of the mounting platforms could beaccommodated. In FIG. 33 d it can be seen that the mounting platforms3305 a, 3305 b and 3305 c are arranged at an angle φ with thelongitudinal axis of the heat sink 3301. The angle φ can be from 0 to 90degrees, from 10 to 80 degrees, from 20 to 70 degrees, from 30 to 60degrees, from 40 to 50 degrees, or about 45 degrees as desired togenerate the densest usable light footprint.

FIG. 34 a depicts a light shield 3401 which may be used in conjunctionwith curing lights of the invention to shield human eyes from lightemitting by the curing light. The light shield includes an orifice 3403through which light from a curing light may pass, the receptacle 3403being formed by the light shield body 3402. A flare 3404 of the shieldperforms most of the protective function.

FIG. 34 b depicts a focus lens 3402 which may be used to focus lightemitted by curing lights of the invention in order to present a denserlight footprint. The focus lens has an outer periphery 3405, a lightentrance side 3506 and a light exit 3507. The focus lens may be designedaccording to known optical principles to focus light output from chipswhich may not be in an optimal pattern for use in dental curing.

FIG. 35 depicts a logic diagram 3501 of circuitry that may be used byAC-powered versions of the invented curing lights. AC power input 3502is provided to a power switch source 3503 which outputs DC power to amain switch 3504. Main switch 3504 powers the control circuit 3505 andthe optional TE cooler 3506 if so equipped. Main switch 3504 alsoprovides a constant current source 3507 for the timer 3508, timer setup3511, timer activation switch 3572 and optional light output beeper3513. Constant current source 3507 also powers the light source 3509 toaccomplish light output 3510.

Referring to FIG. 36, a logic diagram 3601 of circuitry that may be usedby battery-powered versions of the invented curing lights is depicted.AC power input 3602 is provided to a power switch source 3603 whichoutputs DC power to a battery charge unit 3604 that charges battery3605. The battery 3605 powers main switch 3507. Main switch 3607 powersthe control circuit 3608 that controls the optional TE cooler 3610 andthe fan 3609. Main switch 3607 also provides a constant current source3611 for the timer 3613, timer setup 3614, timer activation switch 3615and optional light output beeper 3616. Constant current source 3611 alsopowers the light source 3612 to accomplish light output.

Referring to FIG. 37, a graph of electrical current input I to the lightemitting semiconductor chip(s) of the curing light versus time in apulsed power input scheme is depicted. FIG. 38 depicts a graph of totallight intensity output versus time in order to permit the reader tocompare light intensity output when a current input pulsing scheme suchas that of FIG. 37 is used to a traditional continuous wave currentinput approach which generates a heat effect is used. A pulsed currentinput scheme is used in order to enhance light power output from thechip(s) and in order to avoid light intensity dimunition due to the heateffect. It has been found that when operated in continuous wave mode,the heat effect or heat buildup in the light emitting semiconductorchips will cause a decrease in light output intensity over time, until astabilized light output yield is reached 3802 at point in time 3803. Incontrast, when current input to the semiconductor light source ispulsed, a greater even level of light power output with greaterintensity is achieved 3801. Laboratory experiments have shown thisincreased to be more than 20% in some embodiments, providingsignificantly increased light yield and stable light intensity output inexchange for a simple control modification. Each of the square waves inFIG. 37 is a pulse of current input to the semiconductor light source,measured by “a=duration”, “b=rest period”, and “c=current input level(amps.)”.

Examples of some heat sink materials which may be used in the inventioninclude copper, aluminum, silicon carbide, boron nitride naturaldiamond, monocrystalline diamond, polycrystalline diamond,polycrystalline diamond compacts, diamond deposited through chemicalvapor deposition and diamond deposited through physical vapordeposition. Any materials with adequate heat conductance can be used.

Examples of heat conductive adhesives which may be used are silver basedepoxy, other epoxies, and other adhesives with a heat conductivequality. In order to perform a heat conductive function, it is importantthat the adhesive possess the following characteristics: (i) strongbonding between the materials being bonded, (ii) adequate heatconductance, (iii) electrically insulative or electrically conductive asdesired, and (iv) light reflective as desired. Examples of lightreflective adhesives which may be used include silver and aluminum basedepoxy.

Examples of substrates on which the semiconductors used in the inventionmay be grown include Si, GaAs, GaN, InP, sapphire, SiC, GaSb, InAs andothers. These may be used for both electrically insulative andelectrically conductive substrates.

Materials which may be used to used as a thermoelectric cooler in theinvention include known semiconductor junction devices.

The semiconductor light source of the invention should emit light of awavelength suitable to activate photoinitiators in the compositematerial to be cured.

Heat sinks used in this invention can be of a variety of shapes anddimensions, such as those depicted in the drawings or any others whichare useful for the structure of the particular light source beingconstructed. It should be noted that particular advantage has been foundwhen attaching the semiconductor light source to a small primary heatsink, and then the small primary heat sink is attached to an elongatesecondary heat sink to draw heat away from the semiconductor and awayfrom the patient's mouth.

While the present invention has been described and illustrated inconjunction with a number of specific embodiments, those skilled in theart will appreciate that variations and modifications may be madewithout departing from the principles of the invention as hereinillustrated, described, and claimed.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects as only illustrative,and not restrictive. The scope of the invention is, therefore, indicatedby the appended claims, rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

1. A curing light comprising: a light module, said light moduleincluding an elongate heat sink with a proximal end and a distal end,said elongate heat sink havinga longitudinal axis, a mounting platformlocated at said elongate heat sink distal end, said mounting platformbeing adapted to have a LED chip module mounted thereon, and an LED chipmodule mounted on said mounting platform, said LED chip module includinga primary heat sink, said primary heat sink having a smaller mass thansaid elongate heat sink, a well on said primary heat sink for mountingan LED chip therein, an LED chip mounted in said well, wherein said LEDchip module is mounted on said mounting platform; and wherein saidmounting platform is positioned so light emitted by said LED chip moduledirectly forward of said LED chip module travels away from said LED chipmodule at an angular orientation in the range of 30 to 150 degrees; withrespect to said elongate heat sink longitudinal axis and wherein lightemitted by the curing light travels away from the curing light at anangular orientation in the range of 30 to 150 degrees with respect tosaid elongate heat sink longitudinal axis; and wherein said light exitsthe curing light and travels to a location where it can cure alight-curable material without passing through a light guide.
 2. Acuring light comprising: an elongate heat sink with a proximal end and adistal end, said elongate heat sink having a longitudinal axis definedbetween said proximal end and said distal end, an LED chip modulemounted at said elongate heat sink distal end, said LED chip moduleincluding a primary heat sink, said primary heat sink having a smallermass than said elongate heat sink, and an LED chip mounted to saidprimary heat sink; wherein said LED chip module is mounted on saidmounting platform in a position so that light emitted by said LED chipmodule directly forward of said LED chip module travels away from saidLED chip module at an angle in the range of 45 to 135 degrees withrespect to said elongate heat sink longitudinal axis; wherein said lightexits the curing light and travels to a location where it can cure alight-curable material without passing through a light guide.
 3. Acuring light as recited in claim 2 further comprising a well on saidprimary heat sink wherein said LED chip is mounted.
 4. A curing lightcomprising: an elongate heat sink having a longitudinal axis, asemiconductor chip capable of emitting light that can aid in initiatingcuring of a curable material, wherein said semiconductor chip is fixedlymounted with respect to said elongate heat sink so that light emitted bysaid semiconductor chip directly forward of said semiconductor chipdeparts said semiconductor chip at an angle with respect to saidelongate heat sink longitudinal axis in the range of 30 to 150 degrees;and wherein said light travels to the exterior of the curing light andtravels to a location where it can cure a light-curable material withoutpassing through a light guide.